Method and system for allocating bandwidth based on transmission power of devices transmitting over communications channels in a network

ABSTRACT

A method performed by a central network device, such as a network edge device, or a CMTS, determines whether some of a plurality of user devices coupled to a communication device are transmitting at substantially their respective maximum power output level over a given channel. If the central device determines that some of the devices are operating at near their maximum output level (“power pegged,) the central device searches for another channel that can carry the traffic of the power pegged devices at reduced data rate. If another channel can accommodate transmission of signals of the power pegged device, the central device instructs the power pegged devices to tune to the new channel at a reduced data rate compared to the data rate of the current channel.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority as a Continuation of U.S. patentapplication Ser. No. 13/419,208, entitled “Method and System forAllocating Bandwidth based on Transmission Power of Devices Transmittingover Communications Channels in a Network,” filed Mar. 13, 2012, whichis a Continuation of U.S. patent application Ser. No. 12/258,661,entitled “Method and System for Allocating Bandwidth based onTransmission Power of Devices Transmitting over Communications Channelsin a Network,” filed on Oct. 27, 2008, which issued as U.S. Pat. No.8,136,141 on Mar. 13, 2012, and which claims priority as aNon-Provisional of U.S. Provisional Patent Application Ser. No.60/982,936, entitled “Transmit-power-based load balancing,” which wasfiled Oct. 26, 2007, the disclosures of which are incorporated herein byreference in their entirety.

TECHNICAL FIELD

The claimed subject matter relates to communications networks, and moreparticularly, to using the transmission power of each of a pluralityuser devices over channels of a network to determine which of aplurality of channels the devices should transmit over.

BACKGROUND

As FIG. 1 illustrates, the path between the Cable Modem TerminationSystem (CMTS) and the Cable Modem (CM) has many attenuation points. TheCM needs to transmit enough power such that the signal hits the CMTS ata specific desired power level. The CMTS asks the CM during the rangingprocess (and station maintenance) to adjust (increase or decrease) itstransmitted power so that the received power at the input of the CMTS isequal to the desired value (0 dBmV in FIG. 1).

If the attenuation between the CMTS and CM increases, the CM is asked totransmit more power to keep the received power at the input of the CMTSat the desired level. As more and more attenuation is added on the HFClink (e.g., user puts more splitters inside home), the CM may not beable to transmit enough power to provide a desired received power valueat the input of the CMTS (because of its limited power transmissioncapabilities). These particular modems, which are producing the maximumpower output they are capable of and deliver an upstream signal to theinput of the CMTS in which the power of the upstream signal at the CMTSis less than the desired received power level may be herein referred toas ‘power-pegged modems.’ This term implies that the transmit powerlevel at the modem is pegged to the modem's maximum output power level.Since the signal power arriving at the CMTS from these power-peggedmodems is undesirably low, the ability to receive and demodulate thosesignals can oftentimes be impaired. Oftentimes, the characteristics ofthe channel can be modified via modulation profile changes (ex: lowersymbol rates, lower-order QAM, etc.) to make it easier to receive anddemodulate the arriving low-power signals from the power-pegged modems,but these modified characteristics typically result in a lower bit-ratefor all of the modems on the channel. In other words, thenon-power-pegged modems are being penalized in their bit-rates becauseof the existence of power-pegged modems sharing their upstream channel.On typical upstream channels, most of the modems on the channel will notbe power-pegged, so the penalties will unfortunately be felt by a largepercentage of the modems (which are not power-pegged).

Since the Multiple System Operator (MSO) is required to provide anadequate service to all CMs connected to a CMTS, a modulation profilemust be assigned to a particular upstream channel such that all CMs cancommunicate signals reliably using that modulation profile. Theunfortunate case happens when a very small number of CMs on a certainupstream channel are power-pegged, which results in a low-bit-ratemodulation profile assigned to that upstream channel by the CMTS. Allmodems on that upstream channel will unfortunately be penalized andforced to use the low-rate modulation profile for transmission eventhough most of those modems are non-power-pegged modems and would workwith higher-rate modulation profiles. MSOs normally use the low-ratemodulation profile approach to solve the problems that occur whenever afew modems on an upstream channel are power-pegged.

Assigning low-rate modulation profiles to upstream channels, where mostof the modems are not power-pegged, results in inefficient use of thechannel capacity. We propose in this document a solution to thisproblem.

SUMMARY

We propose to use a novel load-balancing technique based on the modemstransmitted power values. When a predetermined percentage of modems on acertain upstream channel, either a (physical or a logical channel) arepower-pegged, these modems must be moved to another physical or logicalupstream channel. The new upstream channel should have characteristics(narrower width, lower-order modulation profile, specific communicationstechnology) that will permit the power-pegged modems to operate withsatisfactory results. The process of moving/tuning the modems from oneupstream (physical or logical) to another based on the modemstransmitted power is called transmit power load balancing. This type ofload balancing enables the MSO to increase the capacity of the ‘old’, orprevious, upstream channel after removing transmissions frompower-pegged modems therefrom, because most of the remaining modems onthat channel can transmit enough power to operate at high data rates.

Thus, moving power-pegged modems out of upstream channels where mostmodems are not power-pegged, followed by parameter-optimization for thatold upstream channel results in efficient use of the upstream spectrumand a higher capacity system. Transmit power load balancing is alsouseful in reducing the number of bonded upstream channels required toprovide high upstream data rates.

DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an upstream transmission path in a communicationnetwork.

FIG. 2 illustrates a flow diagram of a method for assigning upstreamtransmissions to channels based on the output headroom of transmittingdevices.

FIG. 3 illustrates an upstream transmission path in a communicationnetwork having an edge device located between a central device and thenetwork.

DETAILED DESCRIPTION

As a preliminary matter, it will be readily understood by those personsskilled in the art that the present invention is susceptible of broadutility and application. Many methods, embodiments and adaptations ofthe present invention other than those herein described, as well as manyvariations, modifications, and equivalent arrangements, will be apparentfrom or reasonably suggested by the present invention and the followingdescription thereof, without departing from the substance or scope ofthe present invention.

Accordingly, while the present invention has been described herein indetail in relation to preferred embodiments, it is to be understood thatthis disclosure is only illustrative and exemplary of the presentinvention and is made merely for the purposes of providing a full andenabling disclosure of the invention. The following disclosure is notintended nor is to be construed to limit the present invention orotherwise to exclude any such other embodiments, adaptations,variations, modifications and equivalent arrangements, the presentinvention being limited only by the claims appended hereto and theequivalents thereof.

Returning now to the figures, FIG. 2 illustrates a flow diagram of amethod 200 for assigning the upstream frequencies that a plurality ofuser devices use in transmitting upstream transmissions over acommunication network, such as the network 2 shown in FIG. 1. Method 200starts at step 205 and at step 210, the method determines whether any ofthe user devices, such as cable modems, are transmitting atsubstantially the maximum output power, such that they have no headroomto accommodate an increase in output power. At network edge device mayperform step 210 by sending a request message to the user devices toreturn a message indicating that they are at, or substantially at, theirmaximum transmit output power level. If the edge device determines thatone, or more, of the devices are transmitting at substantially theirmaximum output level, the edge device scans other channels at step 215to determine if other channels may have unused bandwidth capacity. Ifthe edge device determines at step 215 that other channels may haveunused bandwidth capacity, the edge device evaluates scanned channels todetermine if the channels with available bandwidth capacity can be usedto transmit signals from the one, or more, devices currentlytransmitting at, or substantially at, their maximum output. A factor theedge device considers is whether the upstream channels with availablecapacity can accommodate the currently power pegged devices withoutadversely affecting transmission of devices that are currently using thechannel under evaluation.

If the edge device determines that one, or more, channels exist withavailable capacity that can accommodate transmissions from the powerpegged devices, the edge device selects at step 220 the best of thechannels that can accommodate the power pegged device to transmitsignals from the power pegged devices.

At step 225, the edge device instructs the power pegged user devices totune to the selected channel and begin transmitting over it. At step230, edge device modifies transmission over the first, or original,channel to maximize transmission performance over it. Method 200 ends atstep. 235.

The description above discusses an edge device. A CMTS, as shown in FIG.1, may perform the function of an edge device. Or, and edge device maybe a device located logically between a CMTS, and a user device, such asa cable modem. Alternatively, edge device functionality and CMTSfunctionality can be combined in the same device and may process signalsreceived at the same port on an HFC. The Edge device performs certainaggregating functions, such as mixing traffic to and from a CMTS withMPEG video streams from a video server or antenna farm. Thus, withrespect to the description of the method 200 shown in FIG. 2, a CMTS, anedge device, or a combination edge and CMTS device may perform thesteps, regardless of whether the devices performing the functionalityare located physically in the same equipment rack, or remotely from oneanother. FIG. 3 illustrates an edge QAM device 8 located between CMTS 6and hybrid fiber coaxial network (“HFC”) 10. Thus, edge QAM device 8, orCMTS 6 could perform the steps of method 200 described above inconnection with method 200.

These and many other objects and advantages will be readily apparent toone skilled in the art from the foregoing specification when read inconjunction with the appended drawings. It is to be understood that theembodiments herein illustrated are examples only, and that the scope ofthe invention is to be defined solely by the claims when accorded a fullrange of equivalents.

What is claimed is:
 1. A method operable to tune customer premisedevices from a first upstream transmission profile to a second upstreamtransmission profile based on transmit power levels, comprising:identifying a transmission power level associated with an existingcustomer premise device transmitting information to a network edgedevice; measuring a receive power level associated with the existingcustomer premise device, the receive power being measured at the networkedge device; determining whether the transmission power level associatedwith the existing customer premise device exceeds a threshold of thereceive power level associated with the existing customer premisedevice; scanning transmission characteristics of at least one otherupstream transmission profile; selecting from the at least one otherscanned upstream transmission profiles a second upstream transmissionprofile that can accommodate upstream transmissions from the existingcustomer premise device without adversely affecting upstreamtransmissions from customer premise devices that are not operating inexcess of the threshold of their respective transmission and receivepower levels; instructing the existing customer premise devicetransmitting upstream at a power level exceeding a threshold of thereceive power level to begin transmitting upstream on the secondupstream transmission profile; and modifying characteristics of thefirst upstream transmission profile.
 2. The method of claim 1 whereinthe characteristics of an upstream transmission profile include achannel width, modulation profile, and communications technology.
 3. Themethod of claim 1 wherein the upstream transmission profiles consideredin the scanning processes comprise logical channels at same frequency ofthe first upstream transmission profile or physical channels atdifferent frequency from that of the first upstream transmissionprofile.
 4. The method of claim 1 wherein the measure of customerpremise devices transmitting power at the threshold is measureddynamically.
 5. The method of claim 1 wherein the measure of customerpremise devices transmitting power at the threshold is measured perupstream transmission profile.
 6. The method of claim 1 wherein thecustomer premise device comprises a multimedia terminal adapter or acable modem.
 7. A computer-implemented method, comprising: determiningwhether an existing customer premise device is transmitting on a firstupstream transmission profile at a power level exceeding a threshold ofa maximum output power level associated with the customer premisedevice; measuring at a network-edge device the received signal power ofthe customer premise device transmitting at power level exceeding athreshold of its maximum output power level; scanning at least one otherupstream transmission profile to identify characteristics associatedwith the at least one other upstream transmission profile; selectingfrom the at least one other scanned upstream transmission profile asecond upstream transmission profile operable to accommodate upstreamtransmissions from the customer premise device without adverselyaffecting upstream transmissions from other customer premise devices onthe second transmission profile; sending an upstream transmissionprofile change command from the network-edge device to the customerpremise device that is transmitting at a power level exceeding thethreshold of its maximum upstream transmit power level, the upstreamtransmission profile change command instructing the customer premisedevice to tune to the second upstream transmission profile; modifyingtransmission characteristics of the first upstream transmission profilebased on the customer premise device now transmitting on the secondupstream transmission profile.
 8. The method of claim 7 wherein thecharacteristics of an upstream transmission profile includes a channelwidth, modulation profile and communications technology.
 9. The methodof claim 7 wherein the at least one upstream transmission profileconsidered in the scanning processes can be logical channels at a samefrequency as the first transmission profile or physical channels atdifferent frequencies from that of the first transmission profile. 10.The method of claim 7 wherein the measure of customer premise devicestransmitting at a power exceeding the threshold of the maximum powerlevel is measured dynamically.
 11. The method of claim 7 wherein themeasure of customer premise devices transmitting at a power exceedingthe threshold of the maximum power level is measured per upstreamtransmission profile.
 12. The method of claim 7 wherein modifyingtransmission characteristics of the first upstream transmission profilecomprises providing higher throughput to the other devices on the firstupstream transmission profile.
 13. A network-edge device comprisingcomputer-readable media operable to be executed by the network edgedevice, and upon execution being configured to cause the network-edgedevice to: determine whether a customer premise device having anestablished connection to the network edge device is transmitting on afirst upstream transmission profile at a power level exceeding athreshold of its maximum output power level; scan at least one otherupstream transmission profile to identify transmission characteristicsof the at least one other upstream transmission profile; select from theat least one other scanned upstream transmission profile a secondupstream transmission profile that can accommodate upstreamtransmissions from the customer premise device without adverselyaffecting upstream transmissions from other customer premise devicesoperating on the second upstream transmission profile; and send anupstream transmission profile change command from the network-edgedevice to the customer premise device that instructs the customerpremise device to use the second upstream transmission profile.
 14. Thenetwork-edge device of claim 13, wherein the network-edge device isfurther operable to modify transmission characteristics of the firstupstream transmission profile to provide better service to customerpremise devices still transmitting using the first upstream transmissionprofile.
 15. The network-edge device of claim 13, wherein thecharacteristics of upstream channels include the channel width,modulation profile and communications technology.
 16. The network-edgedevice of claim 13, wherein the upstream channels considered in thescanning processes comprise logical channels at same frequency of thefirst channel or physical channels at different frequency from that ofthe first channel.
 17. The network-edge device of claim 13, whereintransmission power level of customer premise devices is measureddynamically.
 18. The network-edge device of claim 13, whereintransmission power level of customer premise devices is measured perupstream channel.